revert ("sched: fair: weight calculations")
Yanmin Zhang reported:
Comparing with kernel 2.6.25, sysbench+mysql(oltp, readonly) has many
regressions with 2.6.26-rc1:
1) 8-core stoakley: 28%;
2) 16-core tigerton: 20%;
3) Itanium Montvale: 50%.
Bisect located this patch:
| 8f1bc385cfbab474db6c27b5af1e439614f3025c is first bad commit
| commit 8f1bc385cfbab474db6c27b5af1e439614f3025c
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date: Sat Apr 19 19:45:00 2008 +0200
|
| sched: fair: weight calculations
Revert it to the 2.6.25 state.
Bisected-by: Yanmin Zhang <yanmin_zhang@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index cfa222a..4aac8aa 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1368,9 +1368,6 @@
*/
#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
-/*
- * delta *= weight / lw
- */
static unsigned long
calc_delta_mine(unsigned long delta_exec, unsigned long weight,
struct load_weight *lw)
@@ -1393,6 +1390,12 @@
return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
}
+static inline unsigned long
+calc_delta_fair(unsigned long delta_exec, struct load_weight *lw)
+{
+ return calc_delta_mine(delta_exec, NICE_0_LOAD, lw);
+}
+
static inline void update_load_add(struct load_weight *lw, unsigned long inc)
{
lw->weight += inc;